Wastney M E, Angelus P, Barnes R M, Subramanian K N
Department of Pediatrics, Georgetown University Medical Center, Washington, District of Columbia 20007, USA.
Am J Physiol. 1996 Nov;271(5 Pt 2):R1452-9. doi: 10.1152/ajpregu.1996.271.5.R1452.
Zinc is an essential nutrient for growth; however, little is known about zinc kinetics (absorption, distribution, and excretion) in preterm infants (< 38-wk gestation). Zinc kinetics were studied in two preterm infants (gestational ages, 32 and 33 wk) following oral or intravenous administration of a stable isotope (70Zn). Plasma, red blood cells (RBC), urine, and feces were sampled for up to 30 days. Isotope enrichment was measured in tissues by inductively coupled plasma (ICP)-mass spectrometry, and zinc was determined by ICP-atomic emission spectrometry. Data were analyzed by compartmental analysis using SAAM31. Zinc intake increased during the studies, and, because body zinc was not in steady state, both tracer (70Zn) and tracee (Zn) data were fitted using analogous models. A model for adults [M. E. Wastney, R. L. Aamodt, W. F. Rumble, and R. I. Henkin. Am. J. Physiol. 251 (Regulatory Integrative Comp. Physiol. 20): R398-R408, 1986] was modified to fit data from the preterm infants. RBC data were fitted using one compartment (vs. 2 in adults), and an adult RBC subsystem was included in the model to account for zinc introduced during blood transfusions. Exchange of zinc between compartments that were not sampled was based on zinc distribution in neonates. Absorption was 42 and 34%, and endogenous fecal excretion, based on intravenous data, was 15 micrograms.kg-1.day-1. The model can be used to quantify changes in zinc kinetics of preterm infants with age, weight, and zinc intake for evaluating nutritional requirements with growth.
锌是生长所必需的营养素；然而，对于早产儿（孕周<38周）的锌动力学（吸收、分布和排泄）了解甚少。在两名早产儿（孕周分别为32周和33周）口服或静脉注射稳定同位素（70Zn）后，对其锌动力学进行了研究。在长达30天的时间里采集血浆、红细胞（RBC）、尿液和粪便样本。通过电感耦合等离子体质谱法测量组织中的同位素富集度，通过电感耦合等离子体原子发射光谱法测定锌含量。使用SAAM31通过房室分析对数据进行分析。在研究过程中锌摄入量增加，由于体内锌未处于稳态，示踪剂（70Zn）和被示踪物（Zn）数据均使用类似模型进行拟合。对成人模型[M. E. Wastney, R. L. Aamodt, W. F. Rumble, and R. I. Henkin. Am. J. Physiol. 251 (Regulatory Integrative Comp. Physiol. 20): R398-R408, 1986]进行了修改以拟合早产儿的数据。红细胞数据使用一个房室进行拟合（与成人的两个房室不同），并且模型中纳入了成人红细胞子系统以解释输血过程中引入的锌。未采样房室之间的锌交换基于新生儿的锌分布。吸收率分别为42%和34%，基于静脉注射数据的内源性粪便排泄量为15微克·千克-1·天-1。该模型可用于量化早产儿锌动力学随年龄、体重和锌摄入量的变化，以评估生长过程中的营养需求。
